The economy of the enterohepatic circulation of bile acids in the baboon. 1. Studies of controlled enterohepatic circulation of bile acids.

A primate model with controlled enterohepatic circulation has been developed which allowed short-term evaluation of bile salt pool size, cycling frequency, and fecal losses. We found that when bile salt secretion into the small bowel was increased above 700 mumol/hr bile acid pool cycling frequency was also increased. The latter allowed short-term regulation of bile salt pool size by affecting increased fecal losses. These compensatory mechanisms were associated with a return of bile acid secretion and cycling frequency to normal usually within 12-24 hours. Conversely, during decreased bile salt secretion, regulation of bile salt pool size was accomplished by decreased pool cycling, which decreased fecal losses. Bile acid secretion into the intestine was therefore a major determinant of bile salt cycling frequency. The latter affected bile salt fecal loss to provide short-term regulation of bile salt pool when feedback regulation of bile salt synthesis was nonoperative.